TableSyncData.h

Classes

TableSyncData -- Class to hold table synchronization data. (full description)

class TableSyncData

Interface

Public Members

TableSyncData()

~TableSyncData()

void write (uInt nrrow, uInt nrcolumn, Bool tableChanged, const Block<Bool>& dataManChanged)

void write (uInt nrrow)

Bool read (uInt& nrrow, uInt& nrcolumn, Bool& tableChanged, Block<Bool>& dataManChanged)

MemoryIO& memoryIO()

uInt getModifyCounter() const

Private Members

TableSyncData (const TableSyncData& that)

TableSyncData& operator= (const TableSyncData& that)

Description

Review Status

Reviewed By:

UNKNOWN

Date Reviewed:

before2004/08/25

Programs:

Tests:

tTable

Prerequisite

class TableLockData

Synopsis

This class keeps counters to synchronize the table data when a table is locked or unlocked.
A few counters are kept by this class:

The numbers of rows in the table.
The number of columns in the table.
The table change counter.
A change counter per data manager.

When a lock on the table is acquired, it reads the sync data from the lock file and determines if anything has changed. If so, the necessary steps are taken to reread the table data when needed.
When a lock on the table is released, it updates and writes the sync data which tells if table data have changed.

This class can also be used for the synchronization of tables and external fillers (see class ExternalLockSync). For this purpose it is sufficient to store the number of rows.

Member Description

TableSyncData()

~TableSyncData()

void write (uInt nrrow, uInt nrcolumn, Bool tableChanged, const Block<Bool>& dataManChanged)

Update the synchronization data and write it into the MemoryIO object. This function is called when a table flush is done to reflect if anything has changed compared to the previous flush.

void write (uInt nrrow)

Update the synchronization data and write it into the MemoryIO object. This function should be used by an external filler when it flushes its data.

Bool read (uInt& nrrow, uInt& nrcolumn, Bool& tableChanged, Block<Bool>& dataManChanged)

Read the synchronization data from the MemoryIO object. This function is called when a lock is acquired to see if table data has to be reread.
It returns False when the MemoryIO object is empty.

MemoryIO& memoryIO()

Get the MemoryIO object. This is used to let LockFile read or write the synchronization data into it.

uInt getModifyCounter() const

Get the modify counter.

TableSyncData (const TableSyncData& that)

Copy constructor is forbidden.

TableSyncData& operator= (const TableSyncData& that)

Assignment is forbidden.